/**
 * Base class that provides a common interface for publishing events. Subclasses are expected to to have a property
 * "events" with all the events defined, and, optionally, a property "listeners" with configured listeners defined.
 *
 * For example:
 *
 *     Ext.define('Employee', {
 *         extend: 'Ext.util.Observable',
 *         constructor: function(config){
 *             this.name = config.name;
 *             this.addEvents({
 *                 "fired" : true,
 *                 "quit" : true
 *             });
 *
 *             // Copy configured listeners into *this* object so that the base class's
 *             // constructor will add them.
 *             this.listeners = config.listeners;
 *
 *             // Call our superclass constructor to complete construction process.
 *             this.callParent(arguments)
 *         }
 *     });
 *
 * This could then be used like this:
 *
 *     var newEmployee = new Employee({
 *         name: employeeName,
 *         listeners: {
 *             quit: function() {
 *                 // By default, "this" will be the object that fired the event.
 *                 alert(this.name + " has quit!");
 *             }
 *         }
 *     });
 */
Ext.define('Ext.util.Observable', {

    /* Begin Definitions */

    requires: ['Ext.util.Event'],

    statics: {
        /**
         * Removes **all** added captures from the Observable.
         *
         * @param {Ext.util.Observable} o The Observable to release
         * @static
         */
        releaseCapture: function(o) {
            o.fireEvent = this.prototype.fireEvent;
        },

        /**
         * Starts capture on the specified Observable. All events will be passed to the supplied function with the event
         * name + standard signature of the event **before** the event is fired. If the supplied function returns false,
         * the event will not fire.
         *
         * @param {Ext.util.Observable} o The Observable to capture events from.
         * @param {Function} fn The function to call when an event is fired.
         * @param {Object} scope (optional) The scope (`this` reference) in which the function is executed. Defaults to
         * the Observable firing the event.
         * @static
         */
        capture: function(o, fn, scope) {
            o.fireEvent = Ext.Function.createInterceptor(o.fireEvent, fn, scope);
        },

        /**
         * Sets observability on the passed class constructor.
         *
         * This makes any event fired on any instance of the passed class also fire a single event through
         * the **class** allowing for central handling of events on many instances at once.
         *
         * Usage:
         *
         *     Ext.util.Observable.observe(Ext.data.Connection);
         *     Ext.data.Connection.on('beforerequest', function(con, options) {
         *         console.log('Ajax request made to ' + options.url);
         *     });
         *
         * @param {Function} c The class constructor to make observable.
         * @param {Object} listeners An object containing a series of listeners to add. See {@link #addListener}.
         * @static
         */
        observe: function(cls, listeners) {
            if (cls) {
                if (!cls.isObservable) {
                    Ext.applyIf(cls, new this());
                    this.capture(cls.prototype, cls.fireEvent, cls);
                }
                if (Ext.isObject(listeners)) {
                    cls.on(listeners);
                }
                return cls;
            }
        }
    },

    /* End Definitions */

    /**
     * @cfg {Object} listeners
     *
     * A config object containing one or more event handlers to be added to this object during initialization. This
     * should be a valid listeners config object as specified in the {@link #addListener} example for attaching multiple
     * handlers at once.
     *
     * **DOM events from Ext JS {@link Ext.Component Components}**
     *
     * While _some_ Ext JS Component classes export selected DOM events (e.g. "click", "mouseover" etc), this is usually
     * only done when extra value can be added. For example the {@link Ext.view.View DataView}'s **`{@link
     * Ext.view.View#itemclick itemclick}`** event passing the node clicked on. To access DOM events directly from a
     * child element of a Component, we need to specify the `element` option to identify the Component property to add a
     * DOM listener to:
     *
     *     new Ext.panel.Panel({
     *         width: 400,
     *         height: 200,
     *         dockedItems: [{
     *             xtype: 'toolbar'
     *         }],
     *         listeners: {
     *             click: {
     *                 element: 'el', //bind to the underlying el property on the panel
     *                 fn: function(){ console.log('click el'); }
     *             },
     *             dblclick: {
     *                 element: 'body', //bind to the underlying body property on the panel
     *                 fn: function(){ console.log('dblclick body'); }
     *             }
     *         }
     *     });
     */
    // @private
    isObservable: true,

    constructor: function(config) {
        var me = this;

        Ext.apply(me, config);

        me.events = me.events || {};
        if (me.listeners) {
            me.on(me.listeners);
            me.listeners = null; //change the prototype in case any are set there.
        }

        if (me.bubbleEvents) {
            me.enableBubble(me.bubbleEvents);
        }
    },

    // @private
    eventOptionsRe : /^(?:scope|delay|buffer|single|stopEvent|preventDefault|stopPropagation|normalized|args|delegate|element|vertical|horizontal|freezeEvent)$/,

    /**
     * Adds listeners to any Observable object (or Ext.Element) which are automatically removed when this Component is
     * destroyed.
     *
     * @param {Ext.util.Observable/Ext.Element} item The item to which to add a listener/listeners.
     * @param {Object/String} ename The event name, or an object containing event name properties.
     * @param {Function} fn (optional) If the `ename` parameter was an event name, this is the handler function.
     * @param {Object} scope (optional) If the `ename` parameter was an event name, this is the scope (`this` reference)
     * in which the handler function is executed.
     * @param {Object} opt (optional) If the `ename` parameter was an event name, this is the
     * {@link Ext.util.Observable#addListener addListener} options.
     */
    addManagedListener : function(item, ename, fn, scope, options) {
        var me = this,
            managedListeners = me.managedListeners = me.managedListeners || [],
            config;

        if (typeof ename !== 'string') {
            options = ename;
            for (ename in options) {
                if (options.hasOwnProperty(ename)) {
                    config = options[ename];
                    if (!me.eventOptionsRe.test(ename)) {
                        me.addManagedListener(item, ename, config.fn || config, config.scope || options.scope, config.fn ? config : options);
                    }
                }
            }
        }
        else {
            managedListeners.push({
                item: item,
                ename: ename,
                fn: fn,
                scope: scope,
                options: options
            });

            item.on(ename, fn, scope, options);
        }
    },

    /**
     * Removes listeners that were added by the {@link #mon} method.
     *
     * @param {Ext.util.Observable/Ext.Element} item The item from which to remove a listener/listeners.
     * @param {Object/String} ename The event name, or an object containing event name properties.
     * @param {Function} fn (optional) If the `ename` parameter was an event name, this is the handler function.
     * @param {Object} scope (optional) If the `ename` parameter was an event name, this is the scope (`this` reference)
     * in which the handler function is executed.
     */
    removeManagedListener : function(item, ename, fn, scope) {
        var me = this,
            options,
            config,
            managedListeners,
            length,
            i;

        if (typeof ename !== 'string') {
            options = ename;
            for (ename in options) {
                if (options.hasOwnProperty(ename)) {
                    config = options[ename];
                    if (!me.eventOptionsRe.test(ename)) {
                        me.removeManagedListener(item, ename, config.fn || config, config.scope || options.scope);
                    }
                }
            }
        }

        managedListeners = me.managedListeners ? me.managedListeners.slice() : [];

        for (i = 0, length = managedListeners.length; i < length; i++) {
            me.removeManagedListenerItem(false, managedListeners[i], item, ename, fn, scope);
        }
    },

    /**
     * Fires the specified event with the passed parameters (minus the event name, plus the `options` object passed
     * to {@link #addListener}).
     *
     * An event may be set to bubble up an Observable parent hierarchy (See {@link Ext.Component#getBubbleTarget}) by
     * calling {@link #enableBubble}.
     *
     * @param {String} eventName The name of the event to fire.
     * @param {Object...} args Variable number of parameters are passed to handlers.
     * @return {Boolean} returns false if any of the handlers return false otherwise it returns true.
     */
    fireEvent: function(eventName) {
        var name = eventName.toLowerCase(),
            events = this.events,
            event = events && events[name],
            bubbles = event && event.bubble;

        return this.continueFireEvent(name, Ext.Array.slice(arguments, 1), bubbles);
    },

    /**
     * Continue to fire event.
     * @private
     *
     * @param {String} eventName
     * @param {Array} args
     * @param {Boolean} bubbles
     */
    continueFireEvent: function(eventName, args, bubbles) {
        var target = this,
            queue, event,
            ret = true;

        do {
            if (target.eventsSuspended === true) {
                if ((queue = target.eventQueue)) {
                    queue.push([eventName, args, bubbles]);
                }
                return ret;
            } else {
                event = target.events[eventName];
                // Continue bubbling if event exists and it is `true` or the handler didn't returns false and it
                // configure to bubble.
                if (event && event != true) {
                    if ((ret = event.fire.apply(event, args)) === false) {
                        break;
                    }
                }
            }
        } while (bubbles && (target = target.getBubbleParent()));
        return ret;
    },

    /**
     * Gets the bubbling parent for an Observable
     * @private
     * @return {Ext.util.Observable} The bubble parent. null is returned if no bubble target exists
     */
    getBubbleParent: function(){
        var me = this, parent = me.getBubbleTarget && me.getBubbleTarget();
        if (parent && parent.isObservable) {
            return parent;
        }
        return null;
    },

    /**
     * Appends an event handler to this object.  For example:
     *
     *     myGridPanel.on("mouseover", this.onMouseOver, this);
     *
     * The method also allows for a single argument to be passed which is a config object
     * containing properties which specify multiple events. For example:
     *
     *     myGridPanel.on({
     *         cellClick: this.onCellClick,
     *         mouseover: this.onMouseOver,
     *         mouseout: this.onMouseOut,
     *         scope: this // Important. Ensure "this" is correct during handler execution
     *     });
     *
     * One can also specify options for each event handler separately:
     *
     *     myGridPanel.on({
     *         cellClick: {fn: this.onCellClick, scope: this, single: true},
     *         mouseover: {fn: panel.onMouseOver, scope: panel}
     *     });
     *
     * @param {String/Object} eventName The name of the event to listen for.
     * May also be an object who's property names are event names.
     *
     * @param {Function} [fn] The method the event invokes.  Will be called with arguments
     * given to {@link #fireEvent} plus the `options` parameter described below.
     *
     * @param {Object} [scope] The scope (`this` reference) in which the handler function is
     * executed. **If omitted, defaults to the object which fired the event.**
     *
     * @param {Object} [options] An object containing handler configuration.
     *
     * **Note:** Unlike in ExtJS 3.x, the options object will also be passed as the last
     * argument to every event handler.
     *
     * This object may contain any of the following properties:
     *
     * @param {Object} options.scope
     *   The scope (`this` reference) in which the handler function is executed. **If omitted,
     *   defaults to the object which fired the event.**
     *
     * @param {Number} options.delay
     *   The number of milliseconds to delay the invocation of the handler after the event fires.
     *
     * @param {Boolean} options.single
     *   True to add a handler to handle just the next firing of the event, and then remove itself.
     *
     * @param {Number} options.buffer
     *   Causes the handler to be scheduled to run in an {@link Ext.util.DelayedTask} delayed
     *   by the specified number of milliseconds. If the event fires again within that time,
     *   the original handler is _not_ invoked, but the new handler is scheduled in its place.
     *
     * @param {Ext.util.Observable} options.target
     *   Only call the handler if the event was fired on the target Observable, _not_ if the event
     *   was bubbled up from a child Observable.
     *
     * @param {String} options.element
     *   **This option is only valid for listeners bound to {@link Ext.Component Components}.**
     *   The name of a Component property which references an element to add a listener to.
     *
     *   This option is useful during Component construction to add DOM event listeners to elements of
     *   {@link Ext.Component Components} which will exist only after the Component is rendered.
     *   For example, to add a click listener to a Panel's body:
     *
     *       new Ext.panel.Panel({
     *           title: 'The title',
     *           listeners: {
     *               click: this.handlePanelClick,
     *               element: 'body'
     *           }
     *       });
     *
     * **Combining Options**
     *
     * Using the options argument, it is possible to combine different types of listeners:
     *
     * A delayed, one-time listener.
     *
     *     myPanel.on('hide', this.handleClick, this, {
     *         single: true,
     *         delay: 100
     *     });
     *
     */
    addListener: function(ename, fn, scope, options) {
        var me = this,
            config,
            event;

        if (typeof ename !== 'string') {
            options = ename;
            for (ename in options) {
                if (options.hasOwnProperty(ename)) {
                    config = options[ename];
                    if (!me.eventOptionsRe.test(ename)) {
                        me.addListener(ename, config.fn || config, config.scope || options.scope, config.fn ? config : options);
                    }
                }
            }
        }
        else {
            ename = ename.toLowerCase();
            me.events[ename] = me.events[ename] || true;
            event = me.events[ename] || true;
            if (Ext.isBoolean(event)) {
                me.events[ename] = event = new Ext.util.Event(me, ename);
            }
            event.addListener(fn, scope, Ext.isObject(options) ? options : {});
        }
    },

    /**
     * Removes an event handler.
     *
     * @param {String} eventName The type of event the handler was associated with.
     * @param {Function} fn The handler to remove. **This must be a reference to the function passed into the
     * {@link #addListener} call.**
     * @param {Object} scope (optional) The scope originally specified for the handler. It must be the same as the
     * scope argument specified in the original call to {@link #addListener} or the listener will not be removed.
     */
    removeListener: function(ename, fn, scope) {
        var me = this,
            config,
            event,
            options;

        if (typeof ename !== 'string') {
            options = ename;
            for (ename in options) {
                if (options.hasOwnProperty(ename)) {
                    config = options[ename];
                    if (!me.eventOptionsRe.test(ename)) {
                        me.removeListener(ename, config.fn || config, config.scope || options.scope);
                    }
                }
            }
        } else {
            ename = ename.toLowerCase();
            event = me.events[ename];
            if (event && event.isEvent) {
                event.removeListener(fn, scope);
            }
        }
    },

    /**
     * Removes all listeners for this object including the managed listeners
     */
    clearListeners: function() {
        var events = this.events,
            event,
            key;

        for (key in events) {
            if (events.hasOwnProperty(key)) {
                event = events[key];
                if (event.isEvent) {
                    event.clearListeners();
                }
            }
        }

        this.clearManagedListeners();
    },

    //<debug>
    purgeListeners : function() {
        if (Ext.global.console) {
            Ext.global.console.warn('Observable: purgeListeners has been deprecated. Please use clearListeners.');
        }
        return this.clearListeners.apply(this, arguments);
    },
    //</debug>

    /**
     * Removes all managed listeners for this object.
     */
    clearManagedListeners : function() {
        var managedListeners = this.managedListeners || [],
            i = 0,
            len = managedListeners.length;

        for (; i < len; i++) {
            this.removeManagedListenerItem(true, managedListeners[i]);
        }

        this.managedListeners = [];
    },

    /**
     * Remove a single managed listener item
     * @private
     * @param {Boolean} isClear True if this is being called during a clear
     * @param {Object} managedListener The managed listener item
     * See removeManagedListener for other args
     */
    removeManagedListenerItem: function(isClear, managedListener, item, ename, fn, scope){
        if (isClear || (managedListener.item === item && managedListener.ename === ename && (!fn || managedListener.fn === fn) && (!scope || managedListener.scope === scope))) {
            managedListener.item.un(managedListener.ename, managedListener.fn, managedListener.scope);
            if (!isClear) {
                Ext.Array.remove(this.managedListeners, managedListener);
            }
        }
    },

    //<debug>
    purgeManagedListeners : function() {
        if (Ext.global.console) {
            Ext.global.console.warn('Observable: purgeManagedListeners has been deprecated. Please use clearManagedListeners.');
        }
        return this.clearManagedListeners.apply(this, arguments);
    },
    //</debug>

    /**
     * Adds the specified events to the list of events which this Observable may fire.
     *
     * @param {Object/String...} eventNames Either an object with event names as properties with
     * a value of `true`. For example:
     *
     *     this.addEvents({
     *         storeloaded: true,
     *         storecleared: true
     *     });
     *
     * Or any number of event names as separate parameters. For example:
     *
     *     this.addEvents('storeloaded', 'storecleared');
     *
     */
    addEvents: function(o) {
        var me = this,
            events = me.events || (me.events = {}),
            arg, args, i;

        if (typeof o == 'string') {
            for (args = arguments, i = args.length; i--; ) {
                arg = args[i];
                if (!events[arg]) {
                    events[arg] = true;
                }
            }
        } else {
            Ext.applyIf(me.events, o);
        }
    },

    /**
     * Checks to see if this object has any listeners for a specified event
     *
     * @param {String} eventName The name of the event to check for
     * @return {Boolean} True if the event is being listened for, else false
     */
    hasListener: function(ename) {
        var event = this.events[ename.toLowerCase()];
        return event && event.isEvent === true && event.listeners.length > 0;
    },

    /**
     * Suspends the firing of all events. (see {@link #resumeEvents})
     *
     * @param {Boolean} queueSuspended Pass as true to queue up suspended events to be fired
     * after the {@link #resumeEvents} call instead of discarding all suspended events.
     */
    suspendEvents: function(queueSuspended) {
        this.eventsSuspended = true;
        if (queueSuspended && !this.eventQueue) {
            this.eventQueue = [];
        }
    },

    /**
     * Resumes firing events (see {@link #suspendEvents}).
     *
     * If events were suspended using the `queueSuspended` parameter, then all events fired
     * during event suspension will be sent to any listeners now.
     */
    resumeEvents: function() {
        var me = this,
            queued = me.eventQueue;

        me.eventsSuspended = false;
        delete me.eventQueue;

        if (queued) {
            Ext.each(queued, function(e) {
                me.continueFireEvent.apply(me, e);
            });
        }
    },

    /**
     * Relays selected events from the specified Observable as if the events were fired by `this`.
     *
     * For example if you are extending Grid, you might decide to forward some events from store.
     * So you can do this inside your initComponent:
     *
     *     this.relayEvents(this.getStore(), ['load']);
     *
     * The grid instance will then have an observable 'load' event which will be passed the
     * parameters of the store's load event and any function fired with the grid's load event
     * would have access to the grid using the `this` keyword.
     *
     * @param {Object} origin The Observable whose events this object is to relay.
     * @param {String[]} events Array of event names to relay.
     * @param {String} [prefix] A common prefix to attach to the event names. For example:
     *
     *     this.relayEvents(this.getStore(), ['load', 'clear'], 'store');
     *
     * Now the grid will forward 'load' and 'clear' events of store as 'storeload' and 'storeclear'.
     */
    relayEvents : function(origin, events, prefix) {
        prefix = prefix || '';
        var me = this,
            len = events.length,
            i = 0,
            oldName,
            newName;

        for (; i < len; i++) {
            oldName = events[i];
            newName = prefix + oldName;
            me.events[newName] = me.events[newName] || true;
            origin.on(oldName, me.createRelayer(newName));
        }
    },

    /**
     * @private
     * Creates an event handling function which refires the event from this object as the passed event name.
     * @param newName
     * @returns {Function}
     */
    createRelayer: function(newName){
        var me = this;
        return function(){
            return me.fireEvent.apply(me, [newName].concat(Array.prototype.slice.call(arguments, 0, -1)));
        };
    },

    /**
     * Enables events fired by this Observable to bubble up an owner hierarchy by calling `this.getBubbleTarget()` if
     * present. There is no implementation in the Observable base class.
     *
     * This is commonly used by Ext.Components to bubble events to owner Containers.
     * See {@link Ext.Component#getBubbleTarget}. The default implementation in Ext.Component returns the
     * Component's immediate owner. But if a known target is required, this can be overridden to access the
     * required target more quickly.
     *
     * Example:
     *
     *     Ext.override(Ext.form.field.Base, {
     *         //  Add functionality to Field's initComponent to enable the change event to bubble
     *         initComponent : Ext.Function.createSequence(Ext.form.field.Base.prototype.initComponent, function() {
     *             this.enableBubble('change');
     *         }),
     *
     *         //  We know that we want Field's events to bubble directly to the FormPanel.
     *         getBubbleTarget : function() {
     *             if (!this.formPanel) {
     *                 this.formPanel = this.findParentByType('form');
     *             }
     *             return this.formPanel;
     *         }
     *     });
     *
     *     var myForm = new Ext.formPanel({
     *         title: 'User Details',
     *         items: [{
     *             ...
     *         }],
     *         listeners: {
     *             change: function() {
     *                 // Title goes red if form has been modified.
     *                 myForm.header.setStyle('color', 'red');
     *             }
     *         }
     *     });
     *
     * @param {String/String[]} eventNames The event name to bubble, or an Array of event names.
     */
    enableBubble: function(eventNames) {
        if (eventNames) {
            var me = this,
                names = (typeof eventNames == 'string') ? arguments : eventNames,
                length = names.length,
                events = me.events,
                ename, event, i;

            for (i = 0; i < length; ++i) {
                ename = names[i].toLowerCase();
                event = events[ename];

                if (!event || typeof event == 'boolean') {
                    events[ename] = event = new Ext.util.Event(me, ename);
                }

                event.bubble = true;
            }
        }
    }
}, function() {

    this.createAlias({
        /**
         * @method
         * Shorthand for {@link #addListener}.
         * @inheritdoc Ext.util.Observable#addListener
         */
        on: 'addListener',
        /**
         * @method
         * Shorthand for {@link #removeListener}.
         * @inheritdoc Ext.util.Observable#removeListener
         */
        un: 'removeListener',
        /**
         * @method
         * Shorthand for {@link #addManagedListener}.
         * @inheritdoc Ext.util.Observable#addManagedListener
         */
        mon: 'addManagedListener',
        /**
         * @method
         * Shorthand for {@link #removeManagedListener}.
         * @inheritdoc Ext.util.Observable#removeManagedListener
         */
        mun: 'removeManagedListener'
    });

    //deprecated, will be removed in 5.0
    this.observeClass = this.observe;

    Ext.apply(Ext.util.Observable.prototype, function(){
        // this is considered experimental (along with beforeMethod, afterMethod, removeMethodListener?)
        // allows for easier interceptor and sequences, including cancelling and overwriting the return value of the call
        // private
        function getMethodEvent(method){
            var e = (this.methodEvents = this.methodEvents || {})[method],
                returnValue,
                v,
                cancel,
                obj = this;

            if (!e) {
                this.methodEvents[method] = e = {};
                e.originalFn = this[method];
                e.methodName = method;
                e.before = [];
                e.after = [];

                var makeCall = function(fn, scope, args){
                    if((v = fn.apply(scope || obj, args)) !== undefined){
                        if (typeof v == 'object') {
                            if(v.returnValue !== undefined){
                                returnValue = v.returnValue;
                            }else{
                                returnValue = v;
                            }
                            cancel = !!v.cancel;
                        }
                        else
                            if (v === false) {
                                cancel = true;
                            }
                            else {
                                returnValue = v;
                            }
                    }
                };

                this[method] = function(){
                    var args = Array.prototype.slice.call(arguments, 0),
                        b, i, len;
                    returnValue = v = undefined;
                    cancel = false;

                    for(i = 0, len = e.before.length; i < len; i++){
                        b = e.before[i];
                        makeCall(b.fn, b.scope, args);
                        if (cancel) {
                            return returnValue;
                        }
                    }

                    if((v = e.originalFn.apply(obj, args)) !== undefined){
                        returnValue = v;
                    }

                    for(i = 0, len = e.after.length; i < len; i++){
                        b = e.after[i];
                        makeCall(b.fn, b.scope, args);
                        if (cancel) {
                            return returnValue;
                        }
                    }
                    return returnValue;
                };
            }
            return e;
        }

        return {
            // these are considered experimental
            // allows for easier interceptor and sequences, including cancelling and overwriting the return value of the call
            // adds an 'interceptor' called before the original method
            beforeMethod : function(method, fn, scope){
                getMethodEvent.call(this, method).before.push({
                    fn: fn,
                    scope: scope
                });
            },

            // adds a 'sequence' called after the original method
            afterMethod : function(method, fn, scope){
                getMethodEvent.call(this, method).after.push({
                    fn: fn,
                    scope: scope
                });
            },

            removeMethodListener: function(method, fn, scope){
                var e = this.getMethodEvent(method),
                    i, len;
                for(i = 0, len = e.before.length; i < len; i++){
                    if(e.before[i].fn == fn && e.before[i].scope == scope){
                        Ext.Array.erase(e.before, i, 1);
                        return;
                    }
                }
                for(i = 0, len = e.after.length; i < len; i++){
                    if(e.after[i].fn == fn && e.after[i].scope == scope){
                        Ext.Array.erase(e.after, i, 1);
                        return;
                    }
                }
            },

            toggleEventLogging: function(toggle) {
                Ext.util.Observable[toggle ? 'capture' : 'releaseCapture'](this, function(en) {
                    if (Ext.isDefined(Ext.global.console)) {
                        Ext.global.console.log(en, arguments);
                    }
                });
            }
        };
    }());
});
